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Buzzihd Beah

In article ,
wrote:

On Sun, 17 Aug 2008 21:51:39 GMT, Buzzihd Beah
wrote:

In article ,
wrote:

On Sun, 17 Aug 2008 05:56:35 GMT, Buzzihd Beah
wrote:

symptoms:

sits at 160 when batteries are off
jerks down slightly when the ignition key turned on
goes up to ~ 175 when the engine warms up

are they fixable at all?

A handy tool for working on these things is a 250 ohm potentiometer.
This will closely match the output of the typical sending units.
Connect one side of the pot to ground and the center wiper to the
gauge on the sender terminal with the sender disconnected. Start at
the center of the pot and sweep it each way to watch the gauge move.
Stay away from the extreme ends because that will probably drive the
gauge into the stops.

Thanks, great idea! Eventually I'll replace the gauge. But, at this
time, what I need to know is that it doesn't get stuck at 175 when the
temp in fact goes higher.

Be sure to get a linear taper pot

Thanks. I just realized that I could also test the sending unit, with an
ohm meter. Do you happen to know, by any chance, what the high/low
resistances are supposed to be, in Mercruiser/GM 5.7? There are numbers
on the 'net for auto engines, but somehow they are not consistent with
each other.

Found this for the Corvette 350 engine, which is the same engine, I
guess:

F Ohm

75 569
80 539
90 477
100 410
110 355
120 300
130 240
140 187
150 171
160 150
170 134
180 123
190 112
200 94
210 83.5
211 83.0